Improvement in psychrometers



2 Sheets--Sheet 1. S. F. HU D D LESTON.

.|W l N LUCK 8L l.

Psychrometers.

Patented March 31,1874.

UNITED STATES PATENT FFICE.

JOSEPII IINLOCK, OF CAMBRIDGE, AND JOHN S. F. IIUDDIiESTON, OF BOSTON,MASSACHUSETTS.

IMPROVEMENT IN PSYCHROMETERS.

Specification forxnirg part of Letters Patent No. 149, [76, dated March3l, 1874; application filed July 3o, 1873.

To all whom it may concern:

Beit known that we, JosEPrI WrNLooK, ot' Cambridge, in the county ot'Middlesex and State of Massachusetts, and JOI-IN S. F. HUD- DLESTON, ot'Boston, in the county of Suffolk and State aforesaid, have invented anImproved Psychrometrical Indicator, of which the following is aspecification:

The object of the present invention is to provide a simple, efficient,and convenient means of determining the relative humidity of theatmosphere or the dew-point, so called, without calculation. Theimprovements are fully hereinafter described and claimed.

In the accompanying plates of drawings our improved psychometricalindica-tor is illustrated.

In Ilate l, Figure 1 is a face view of the dry and wet bulb thermometerswith our indicator adapted thereto; Fig. 2, a transverse horizontalsection in plane of line x x, Fig. l. In Plate 2, Fig. 3 is a'plan viewof the diagram of figures adapted for the indicator 5 Fig. 4, a viewshowing both the degrees of saturation and the dew-point of the air.

A and B in the drawings represent, respectivcly, a wet and a dry bulbthermometer, constructed in the usual manner; C, the stl-in g or wickingdepending from the muslin surrounding the wet bulb I) of the thermometerA into the water in the cup E; F, a cylinder, adapted to be freelyturned by means of a handle or knob, H, in the casing G. The cylinder Fis provided with a series of columns of iigures, such as shown in Fig.3, Plate 2, and these columns are numbered from one (l) to twenty-two(22) inclusive. Each number from one (l) to twenty-two (22) representsthe difference bctween the degree of temperature indicated by thedry-bulb thermometer B and the degree indicated by the wet-bulbthermometer A. The iigures of each column of figures are arranged oneabove another, (see Fig. 3, Plate 2,) and the several figures in eachcolumn are the results of calculation, and give, for any degree ofthewet-bulb thermometer A, the amount of moisture in the air; or, in otherwords, the degree of saturation of the air, or both the amount ofmoisture in or the dew-point of the air for any dili'erence between theindica-tions of a wet-bulb thermometer and a dry-bulb thermometer, fromone (1) to twenty-two (22) inclusive. The casing serves as a support, in

the present instance, for the two thermometers, as well as for thecylinder, and is secured to the base L. I, the slit or opening. On theleft of this slit I, iixed to the casing G, is the scale J, which, inthis instance, conforms to the scale of the wet-bulb thermometer. Theiigures of the several columns of figures are arranged in parallelhorizontal lines, correspondingly to the divisions of the ixed scale J,the number or ligure to be produced as showing the amount of moisture inthe air or dew-point being each placed in line horizontally with thedegree on the xed scale corresponding to the degree as indicated on thewet-bulb thermometer, in the column of gures having at its head theligure corresponding to the difference in degrees between the degreesindicated by the readings of the dry and wet bulb thermometers.

To ascertain the moisture in the air, having properly prepared thewet-bulb thermometer, observe the height of the mercury, which, forexample, suppose to be 600, and then observe the height of the mercuryof dry-bulb thermometer, which, for example, suppose to be 720. Subtractthe former, 60, from the latter, 72, and then turn the cylinder untilthat column of the columns of gures on the cylinder F comes to thecasing-slit I, which, in its number, corresponds to the dierence between6() and r2that is, bring the column marked 12, with red ink, to theslit, and, opposite the line of division marked 60 of the xed scale Jobserve the number indicated in the said column of figures, whichnumber, 46, is the per centum of moisture in air, as shown at a, Fig. l.

For all degrees of the dry and wet bulb thermometers proceed as above,and the result sought for will be shown by the indicator.

A similar arrangement of indicator may be also adapted by simply achange of figures in the several columns for indicating the dewpoint ofthe air; or, by a double column of ligures, as shown in Fig. 4, undereach division, the indicator may be adapted to show both the dew-pointand the degree of saturation; or by t\vo separate cylinders, to be usedor operated independently.

As in Fi 4, the left column shovvs the degree of saturation, and theright column the dew-point, and, carrying out the same illustration, inline to the right of 600 on xed scale, and With 4G, the per centum ofmoisture in the air will be found 3i-the dew-point for the sametemperature.

The numbers of the columns, one to tvventy two, are printed in red ink,and the others in black ink, for the purpose of distinction, and ofquickly discerning them; but they can all be of the same, or ot' anytivo, colors desired.

rJlhe fixed scale J, instead of corresponding to theivet-bulb-thermometer scale, can be read as answering` to the dry-bulbthermometer. Of course, the columns of gures relatively so much higheron the scale-that is, the fortysix degrees ascertained, as above-in lieuof being opposite to 60 would then be against or inline of 72; but ivefind it better and more convenient to use the Wet-bulb-thermometerscale.

In lieu of having a separate scale for the cylinder, it could be soadapted that the cylinder could revolve in connection with the Wet ordry bulb thermometer scales.

The frame or standard to support the cylinder and thermometer cau bemade from any kinds of Woods or metal, and of any form or shape,ornamented as desired.

The cylinder F could revolve horizontally, iu`lieu ot' vertically, asdescribed.

Having thus described our invention, what We claim, and desire to secureby Letters latent, is

The instrument herein described, the saine consisting of the ivet-bulbthermometer A, the dry-bulb thermometer B, the cylinder F, providedWiththe tabulated columns ofiigures, and revolving Within a casing, Gr,having a slit, I, and scale J, all arranged in the relation to eachother, substantially as shoivn and described.

' JOSEPH \Y1NL()CK.

JOHN S. F. IIUDDLESTOX.

Witnesses:

EDWIN W. BROWN, J. P. HeELRov.

